Crimpable insulated connector with crimping tool locating means



March 16, 1965 A. c. NEADERLAN NSULAT ED CONNECTOR WITH CRIMPING TOOLLOCATING MEANS Filed NOV. 27 1962 CRIMPABLE I 2J FI 6 4 INVENToR ADoLPHc. N o AND BY ATTO NEY United States Patent 3,173,989 CRllVIPABLEINSULATED CONNECTOR WITH CRIMIING TOOL LOCATING MEANS Adolph C.Neaderland, Norwalk, Conn., assignor to Burndy Corporation, acorporation of New York Filed Nov. 27, 1962, Ser. No. 240,355 Claims.(Cl. 174-84) This invention relates to electrical connectors havingtubular malleable metal bodies and coaxially disposed insulatingsleeves, and, more particularly, to electrical connectors of the type inwhich the tubular body is indented or crimped to a wire by a tool actingthrough the insulating material.

In connectors of this type in which a number of longitudinally spacedcrimps are successively formed, it is desirable that the crimps beuniformly spaced apart. Uniform spacing avoids overlapping or excessivespacing between adjacent crimps, both of which tend to reduce thestrength of the crimped connection and also may overstress and tear orpuncture the insulating sleeve.

An insulated connector of this type is known in which the insulatingsleeve is provided with a plurality of peripheral ridges for positioningand spacing the successive crimps. The ridged sleeve fully performs itsstated functions, namely guiding and positioning the crimping tool,inhibiting longitudinal cracking and tearing of the sleeve duringcrimping, and increasing the strength of the tube to preserve itscircular cross-section during storage independent of the inner metaltube. But it has been learned that with some insulating materials usedin this configurar tion, transverse cracks are produced at the base ofthe ridges on the sleeve during crimping.

Accordingly it is a principal object of this invention to provide aninsulated electrical connector having improved means for positioning acrimping tool while inhibiting longitudinal and transverse cracking ofthe insulating cover.

This and other objects and features of this invention will be made moreapparent by reference to the following description taken in conjunctionwith the accompanying drawings, in which:

FIGURE 1 is a perspective view of an electrical connector havingcrimping guides formed in accordance with this invention;

FIGURE 2 is a perspective view of an insulated electrical connectorshowing another embodiment of the invention;

FIGURE 3 is a similar perspective view showing yet another embodiment;and

FIGURE 4 is a longitudinal cross-sectional view of the connector ofFIGURE 3 with conductors inserted, showing its condition before andafter crimping.

Referring now more particularly to the drawings, reference numeralindicates a malleable metal tube having an axial obstruction orpartition 12, which limits the extent of insertion of a conductor suchas 14 into the tube, and, in the embodiment illustrated, forms a pair ofconductor receiving sockets 16 and 18. Coaxial about the tube 10 is aninsulating sleeve 20 extending over the full length of the tube, thetube and sleeve in combination forming an insulated electrical connectorfor use with a compression tool.

The tube may be provided with an external groove adapted to engage aninternal bead 17 on the sleeve to hold the two together, although otherinterlocking or fastening means may be used. An oxide inhibitingcompound may be disposed within the tube to insure good electricalconnections, and a pair of end caps 13 provided to retain the compound.The end caps may be made of an insulating, resilient material so that aninternal groove or grooves 28 may be snapped into place over aperipheral ice bead or beads 30 on the sleeve ends to lock the capsthereto, and so that the conductors to be inserted into the sockets maybe inserted through the caps as will be described below. The insulatingsleeve may be of any well known material, such as nylon, which isadapted to transmit compressive crimping forces without rupturing.

The outer surface of the sleeve 20a bears a series of integrally molded,substantially uniformly spaced apart, sets of radial projections such asthe peripherally scalloped ridges or beads 32, shown in FIGURE l. In theembodiment shown in FIGURE 2, the low points or valleys 22 between thetin-shaped projections or scallops 33 on the surface of sleeve 2Gb, aremade flush with the outer sleeve surface, producing in effect, a seriesof axially spaced rings of independent radial projections. FIGURE 3represents a still further modification, in which the radial projectionsare in the form of roughly conically-shaped nubs 36.

The projections function as tactile guides for positioning the crimpingtool on the sleeve. They may be made of suicient height so as to preventtheir being accommodated within the jaws of the tool, to insureengagement of the jaws on the sleeve in between adjacent sets ofprojections only. To enhance their positioning operation, theprojections may also be made with tapered or sloped transverse sidesurfaces as in FIGURES 2 and 3, so that adjacent projections form aguide for ailirmatively positioning the jaws of a crimping tool betweenthem. The projections thus insure that each succeeding crimp will beproperly spaced from the preceding one.

By providing sleeve portions of increased cross-sectional area, i.e.,the inner diameter of the sleeve is substantially uniform while theouter diameter is increased in the area of the projections, theprojections act to prevent the spreading or propagation of longitudinalcracks, such as are caused by crimping, by in effect providingreinforced obstructions spaced along the sleeve surface, and byproviding additional material which may be drawn into compressed andweakened areas by cold plastic iiowi Prevention of the spreading oflongitudinal cracks is further improved by arranging alternate sets ofprojections in alternating angular position as in FIGURE l, so that nounobstructed longitudinal path extends along the sleeve for more thanthe distance between two adjacent sets of projections.

The uniformly shaped peripheral ridges previously known, however, tendto produce stress concentrations at their juncture with the sleevesurface during crimping which often result in transverse cracks in thesleeve. This invention, by substantially reducing, or eliminatingentirely, the cross sectional area of the ridges at circumferentiallyspaced apart points, reduces the build-up of longitudinally alignedstresses and has been found to substantially eliminate transversecracking.

As indicated in FIGURE 4, the end caps 13 may be interlocked to thesleeve 20 so that the annular face 26 of the cap is spaced from theend-most set of projections in position to receive a crimping tooltherebetween and to externally and tactilely delimit the length of thesocket into which crimps are to be made. An area of reduced thickness38, adapted to be punctured by the conductor 14 inserted therethrough,is molded into the face of each end cap. Due to its resilientcharacteristics, the cap material surrounding the punctured openinggrips and retains the insulating jacket 11 of the inserted conductor 14,as at 24, and forms moisture-proof insulating seal. The connector isinstalled after the end caps have been placed on the ends of the sleeveso that the grooves 28 interlock with the beads 30. A conductor, with abare end portion of proper length, is inserted through the reducedcross-sectional area 38 of each end cap until the end of the conductorabuts against the axial obstruction 12. A crimping tool is then appliedbetween adjacent sets of projections to produce successive indentations35. The successive crimps permanently deform the malleable tube 10 intoengagement with each of the conductors to produce a secure, fullyinsulated electrical and mechanical connection.

The invention has thus been described but it is desired to be understoodthat it is not conned to the particular forms or usages shown anddescribed, the same being merely illustrative, and that the inventionmay be carried out in other ways without departing from the spirit ofthe invention; therefore, the right is broadly claimed to employ allequivalent instrumentalities coming within the scope of the appendentclaims, and by means of Which objects of this invention are attained andnew results accomplished, as it is obvious that the particularembodiments herein shown and described are only some of the many thatcan be employed to obtain these objects and accomplish these results.

I claim:

1. An insulated electrical connector for use with a compression tool,comprising:

a malleable metal tube forming a conductor receiving socket in theinterior thereof;

a sleeve of insulating material circumjacent the outer surface of saidtube;

said sleeve including a plurality of longitudinally spaced aparttransverse cross-sectional areas having portions of increased wallthickness forming integral radial projections on the outer surfacethereof for positioning the jaws of a compression tool applied thereto;

Cil

said portions of increased thickness in each of said crosssectionalareas being peripherally spaced about the circumference of said tube andbeing separated by portions of less than said increased wall thicknessto relieve the build-up of longitudinally aligned stresses which areotherwise caused by portions of increased thickness during crimping.

2. The electrical connector of claim 1 wherein the transversely alignedsurfaces of said projections taper inwardly toward the outer endsthereof.

3. The electrical connector of claim 1 wherein each cross-sectional areadefines a peripheral rib formed on the outer surface of the tube, havinga scallop-shaped outer periphery.

4. The electrical connector of claim 1, wherein the projections inalternate ones of said cross-sectional areas are longitudinally alignedwith each other intermediate the projections of each adjacent area.

5. The electrical connector of claim 1, wherein each of saidcross-sectional areas includes a plurality of individual, elongaten-shaped members separately positioned on the outer surface of saidsleeve.

References Cited in the tile of this patent UNITED STATES PATENTS2,259,261 Miller et al Oct. 14, 1941 2,958,723 Logan et al Nov. 1, 19623,665,292 Chickvary Nov. 20, 1962

1. AN INSULATED ELECTRICALY CONNECTOR FOR USE WITH A COMPRESSION TOOL,COMPRISING: A MALLEABLE METAL TUBE FORMING A CONDUCTOR RECEIVING SOCKETIN THE INTERIOR THEREOF; A SLEEVE OF INSULATING MATERIAL CIRCUMJACENTTHE OUTER SURFACE OF SAID TUBE; SAID SLEEVE INCLUDING A PLURALITY OFLONGITUDINALLY SPACED APART TRANSVERSE CROSS-SECTIONAL AREAS HAVINGPORTION OF INCREASED WALL THICKNESS FORMING INTEGRAL RADIAL PROJECTIONSON THE OUTER SURFACE THEREOF FOR POSITIONING THE JAWS OF A COMPRESSIONTOOL APPLIED THERETO; SAID PORTIONS OF INCREASED THICKNESS IN EACH OFSAID CROSSSECTIONAL AREAS BEING PERIPHERALLY SPACED ABOUT THECIRCUMFERENCE OF SAID TUBE AND BEING SEPARATED BY PORTIONS OF LESS THANSAID INCREASED WALL THICKNESS TO RELIEVE THE BUILD-UP OF LONGITUDINALLYALIGNED STRESSES WHICH ARE OTHERWISE CAUSED BY PORTIONS OF INCRESEDTHICKNESS DURING CRIMPING.